Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D239/00—Heterocyclic compounds containing 1,3-diazine or hydrogenated 1,3-diazine rings
  • C07D239/02—Heterocyclic compounds containing 1,3-diazine or hydrogenated 1,3-diazine rings not condensed with other rings
  • C07D239/24—Heterocyclic compounds containing 1,3-diazine or hydrogenated 1,3-diazine rings not condensed with other rings having three or more double bonds between ring members or between ring members and non-ring members
  • C07D239/26—Heterocyclic compounds containing 1,3-diazine or hydrogenated 1,3-diazine rings not condensed with other rings having three or more double bonds between ring members or between ring members and non-ring members with only hydrogen atoms, hydrocarbon or substituted hydrocarbon radicals, directly attached to ring carbon atoms
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C255/00—Carboxylic acid nitriles
  • C07C255/01—Carboxylic acid nitriles having cyano groups bound to acyclic carbon atoms
  • C07C255/32—Carboxylic acid nitriles having cyano groups bound to acyclic carbon atoms having cyano groups bound to acyclic carbon atoms of a carbon skeleton containing at least one six-membered aromatic ring
  • C07C255/37—Carboxylic acid nitriles having cyano groups bound to acyclic carbon atoms having cyano groups bound to acyclic carbon atoms of a carbon skeleton containing at least one six-membered aromatic ring the carbon skeleton being further substituted by etherified hydroxy groups
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C255/00—Carboxylic acid nitriles
  • C07C255/45—Carboxylic acid nitriles having cyano groups bound to carbon atoms of rings other than six-membered aromatic rings
  • C07C255/46—Carboxylic acid nitriles having cyano groups bound to carbon atoms of rings other than six-membered aromatic rings to carbon atoms of non-condensed rings
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K19/00—Liquid crystal materials
  • C09K19/04—Liquid crystal materials characterised by the chemical structure of the liquid crystal components, e.g. by a specific unit
  • C09K19/06—Non-steroidal liquid crystal compounds
  • C09K19/08—Non-steroidal liquid crystal compounds containing at least two non-condensed rings
  • C09K19/10—Non-steroidal liquid crystal compounds containing at least two non-condensed rings containing at least two benzene rings
  • C09K19/20—Non-steroidal liquid crystal compounds containing at least two non-condensed rings containing at least two benzene rings linked by a chain containing carbon and oxygen atoms as chain links, e.g. esters or ethers
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K19/00—Liquid crystal materials
  • C09K19/04—Liquid crystal materials characterised by the chemical structure of the liquid crystal components, e.g. by a specific unit
  • C09K19/06—Non-steroidal liquid crystal compounds
  • C09K19/08—Non-steroidal liquid crystal compounds containing at least two non-condensed rings
  • C09K19/10—Non-steroidal liquid crystal compounds containing at least two non-condensed rings containing at least two benzene rings
  • C09K19/20—Non-steroidal liquid crystal compounds containing at least two non-condensed rings containing at least two benzene rings linked by a chain containing carbon and oxygen atoms as chain links, e.g. esters or ethers
  • C09K19/2007—Non-steroidal liquid crystal compounds containing at least two non-condensed rings containing at least two benzene rings linked by a chain containing carbon and oxygen atoms as chain links, e.g. esters or ethers the chain containing -COO- or -OCO- groups
  • C09K19/2021—Compounds containing at least one asymmetric carbon atom
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K19/00—Liquid crystal materials
  • C09K19/04—Liquid crystal materials characterised by the chemical structure of the liquid crystal components, e.g. by a specific unit
  • C09K19/06—Non-steroidal liquid crystal compounds
  • C09K19/08—Non-steroidal liquid crystal compounds containing at least two non-condensed rings
  • C09K19/30—Non-steroidal liquid crystal compounds containing at least two non-condensed rings containing saturated or unsaturated non-aromatic rings, e.g. cyclohexane rings
  • C09K19/3001—Cyclohexane rings
  • C09K19/3066—Cyclohexane rings in which the rings are linked by a chain containing carbon and oxygen atoms, e.g. esters or ethers
  • C09K19/3068—Cyclohexane rings in which the rings are linked by a chain containing carbon and oxygen atoms, e.g. esters or ethers chain containing -COO- or -OCO- groups
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K19/00—Liquid crystal materials
  • C09K19/04—Liquid crystal materials characterised by the chemical structure of the liquid crystal components, e.g. by a specific unit
  • C09K19/06—Non-steroidal liquid crystal compounds
  • C09K19/34—Non-steroidal liquid crystal compounds containing at least one heterocyclic ring
  • C09K19/3441—Non-steroidal liquid crystal compounds containing at least one heterocyclic ring having nitrogen as hetero atom
  • C09K19/345—Non-steroidal liquid crystal compounds containing at least one heterocyclic ring having nitrogen as hetero atom the heterocyclic ring being a six-membered aromatic ring containing two nitrogen atoms
  • C09K19/3458—Uncondensed pyrimidines
  • C09K19/3463—Pyrimidine with a carbon chain containing at least one asymmetric carbon atom, i.e. optically active pyrimidines
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C2601/00—Systems containing only non-condensed rings
  • C07C2601/02—Systems containing only non-condensed rings with a three-membered ring
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C2601/00—Systems containing only non-condensed rings
  • C07C2601/12—Systems containing only non-condensed rings with a six-membered ring
  • C07C2601/14—The ring being saturated

Definitions

• the present invention relates to a novel optically active compound, an intermediate therefor, a process for producing the intermediate, and a liquid-crystal composition. More particularly, it relates to a ferroelectric liquid-crystal display material having excellent response and memory characteristics.
• Liquid-crystal display devices are now used extensively owing to their excellent characteristics (low-voltage operation; small power consumption; thin displays can be constructed; displays can be used in bright light and do not cause the viewer to suffer eyestrain).
• the most commonly used TN type display system is very slow in response compared to light-emitting display systems such as the CRT type and, further, it cannot memorize the information being displayed after the applied electric field is removed (it has no memory effect). Because of these disadvantages, many limitations have been imposed on the applications of the TN type displays to a light shutter that is required to have high-speed response characteristics, a printer head, dynamic pictures that should be driven time-division-wise, such as those in TVs etc. Therefore, the TN type displays are unsuited for these applications.
• ferroelectric liquid crystals are expected to be a next-generation liquid-crystal display device and studies and developments are currently being made extensively.
• the liquid-crystal phases of ferroelectric liquid crystals belong to the chiral smectic phases of the tilt type, but from the practical standpoint, those exhibiting a chiral smectic C (hereinafter referred to as Sc * ) phase, which is the lowest in viscosity among the chiral smectic phases, are most preferable.
• Sc * chiral smectic C
• liquid-crystal compounds that exhibit an Sc * phase have been synthesized and studied.
• such liquid-crystal materials are required to: (A) exhibit an Sc* phase over a wide temperature range including room temperature; (B) have a proper phase sequence on the high-temperature side of the Sc* phase, with the helical pitch thereof being large, in order to obtain good orientation; (C) have proper tilt angles; (D) have low viscosities; and (E) show spontaneous polarization that is strong to some degree.
• liquid-crystal compound which alone satisfies all of these requirements.
• an Sc * compound such a liquid-crystal compound exhibiting an Sc* phase (hereinafter referred to as an Sc * compound) is blended with other Sc * compound(s) etc. and used as a liquid-crystal composition that exhibits an Sc* phase (hereinafter referred to as an Sc * liquid-crystal composition).
• an Sc * compound is required to have a low viscosity and to show spontaneous polarization not lower than a certain level, particularly in order to attain high-speed response.
• an optically active compound as a chiral dopant to other liquid-crystal compound or composition that shows a smectic C (hereinafter referred to as Sc) phase and to use the resulting mixture as an Sc* liquid-crystal composition. Since liquid-crystal compositions obtained by this method can have low viscosities, higher-speed response is attainable and, hence, this method is commonly employed. Although the compound to be used as a chiral dopant is not necessarily required to per se exhibit an Sc* phase, compositions containing the compound should have the properties (A) to (E) as specified above with showing an Sc * phase.
• the conventional Sc * compounds have insufficient performances with respect to viscosity, induced spontaneous polarization and helical pitch, etc. and, hence, have failed to provide liquid-crystal materials with good high-speed response characteristics. Therefore, there has been a desire for improvement of such conventional Sc * compounds.
• the liquid-crystal compound should contain a group with a strong dipole moment at a position that is as close as possible to the core of the liquid-crystal compound molecule and also to an asymmetric carbon.
• carbonyl group is generally known as a group having a strong dipole moment
• cyano group can be mentioned as a group having an even stronger dipole moment.
• JP-A means an "unexamined published Japanese patent application”
• JP-A means an "unexamined published Japanese patent application”
• a compound represented by the formula Dislosed in U.S. Patent 4,777,280 and in Walba et al., J. Org. Chem., 54, 4339(1989)
• an object of the present invention is to provide an optically active compound which, when added as chiral dopant to a base liquid crystal showing an Sc phase or Sc * phase, can induce strong spontaneous polarization and also induce a large helical pitch.
• Other objects of the present invention are to provide a ferroelectric liquid-crystal display material which can attain high-speed response and shows excellent orientation characteristics, and further to provide an intermediate for the above optically active compound and a process for producing the intermediate.
• an optically active compound represented by the following general formula (I) wherein R1 represents an alkyl, alkoxyl, or alkoxyalkanoyloxy group which has 1 to 18, preferably 3 to 12, carbon atoms and may be substituted with fluorine, chlorine, or cyano group; R2 represents an alkyl group having 1 to 18, preferably 1 to 8, carbon atoms; m is 0 or 1; Y represents a single bond, -CH2O-, or -COO-; Z represents a single bond or -COO-; and C* and C ** each independently represents an asymmetric carbon atom of the (R) or (S) configuration.
• R1 represents an alkyl, alkoxyl, or alkoxyalkanoyloxy group which has 1 to 18, preferably 3 to 12, carbon atoms and may be substituted with fluorine, chlorine, or cyano group
• R2 represents an alkyl group having 1 to 18, preferably 1 to 8, carbon atoms
• m is 0 or 1
• optically active compound preferably is represented by general formula (I) in which is selected from the group consisting of
• liquid-crystal composition containing the novel optically active compound represented by the above general formula (I).
• the liquid-crystal composition according to the present invention contains, as a constituent, at least one compound represented by general formula (I) given above.
• an Sc * liquid-crystal composition is suited in which at least one compound represented by the above general formula (I) has been incorporated as part or all of the chiral dopant in a base liquid crystal that is the main ingredient and exhibits an Sc phase.
• the cyano group-containing optically active compound of general formula (I) given above can be produced as follows.
• the compound can be easily synthesized by reacting a compound represented by general formula (II)a given below with an acid chloride represented by general formula (VI)a given below in the presence of a base such as pyridine.
• the optically active compound may be obtained by reacting a compound of general formula (II)a with a carboxylic acid represented by general formula (VII)a given below in the presence of a condensation agent such as dicyclohexylcarbodiimide (DCC).
• DCC dicyclohexylcarbodiimide
• the optically active compound can, for example, be produced by reacting a compound of general formula (II)a with a halide represented by general formula (VIII)a given below in the presence of a silver salt such as silver tetrafluoroborate.
• a silver salt such as silver tetrafluoroborate.
• the optically active compound can be easily produced by reacting a compound represented by general formula (II)b given below with an acid chloride represented by general formula (VI)b given below in the presence of a base such as pyridine.
• the optically active compound may be obtained by reacting a compound of general formula (II)b with a carboxylic acid represented by general formula (VII)b given below in the presence of a condensation agent such as dicyclohexylcarbodiimide (DCC).
• DCC dicyclohexylcarbodiimide
• the phenol derivative of general formula (II), which is an optically active compound having a cyano group, also is a novel compound. This compound and a process for the production thereof are also provided by the present invention.
• the compound of general formula (IV) is obtained in the form of a diastereomeric mixture, the isomers can be separated from each other by ordinary separation techniques such as, for example, silica gel column chromatography.
• Each isomer obtained is then tosylated at the OH group by use of p-toluenesulfonyl chloride in the presence of pyridine.
• the resulting tosyl group-containing compound is reacted with a strong base to obtain a compound represented by general formula (V) given below.
• the compounds of general formulae (VI)a, (VI)b, (VII)a, and (VII)b are mostly already known, and may be obtained by ordinary synthesizing techniques.
• the compounds of general formula (VIII)a may alternatively be obtained by reducing the compound of general formula (VI)a or (VI)b and then brominating the reduced compound.
• optically active compound of general formula (I) can be obtained as described above.
• Specific compounds which belong to such compound of general formula (I) and intermediates for the optically active compound which are represented by general formula (II) can be identified by means of measurement of melting point and other phase transition temperatures, infrared spectrophotometry (IR), nuclear magnetic resonance spectroscopy (NMR), mass spectrometry (MS), etc.
• One of the excellent features of the compound of general formula (I) is that it induces a sufficiently large spontaneous polarization (P S ).
• an Sc * liquid-crystal composition consisting of 10% by weight (hereinafter all percents are by weight) of the compound obtained in Example 14 given later and 90% of a base liquid crystal showing an Sc phase and an Sc* liquid-crystal composition consisting of 10% of the compound obtained in Example 24 given later and 90% of the same base liquid crystal have Ps values as large as 13.8 and 9.1 nC/cm2, respectively, at 25°C.
• Sc * compounds derived from (S)-2-methylbutanol such as, for example, (S)-2-methylbutyl p-decyloxybenzylideneaminobenzoate (DOBAMBC), which are the most commonly used asymmetric sources for liquid crystals, have Ps values of about 4 nC/cm2 even when used alone.
• the reason for such large Ps values for the compounds of this invention may be that the asymmetric center of the compound of general formula (I) is directly bonded to the core of the liquid-crystal compound molecule and also to the cyano group which has a strong dipole moment, and that the free rotation about the molecule axis is inhibited by the cyclohexane ring on the adjacent asymmetric carbon.
• the chiral groups at both sides are thought to produce a considerable synergistic effect.
• the compound of general formula (I) according to the present invention has another advantage that by suitably selecting the absolute configuration of each asymmetric carbon, the compound can be made to induce a very large helical pitch.
• an Sc* liquid-crystal composition consisting of 10% of the compound of Example 21 given later and 90% of a base liquid crystal showing an Sc phase and an Sc* liquid-crystal composition consisting of 10% of the compound of Example 24 given later and 90% of the same base liquid crystal show, in their N * phase state, helical pitches that are too large to measure. Such large helical pitches eliminate the necessity of the troublesome helical pitch adjustment.
• an Sc* composition with good orientation characteristics can be obtained only by incorporating the optically active compound of this invention into a base liquid crystal.
• the compound of general formula (I) according to the present invention is suited rather for use as a dopant to give a liquid-crystal composition than for use alone.
• a chiral dopant consisting of at least one optically active compound of general formula (I) and, according to need, other optically active compound(s) is added to other liquid-crystal compound or composition.
• the optically active compound of this invention be added as a chiral dopant to a base liquid-crystal compound or composition which shows an Sc phase but is not chiral.
• the optically active compound of general formula (I) has the property of inducing a sufficiently large spontaneous polarization as described above, incorporation of 1 to 2% or more of the optically active compound into an Sc liquid crystal enables the resulting composition to show a certain degree of induced spontaneous polarization and to attain high-speed response. Even if the compound of general formula (I) per se does not show an Sc * phase, incorporation thereof never narrows the range of temperatures at which the liquid-crystal composition exhibits an Sc * phase.
• the compound of general formula (I) can be incorporated into nematic liquid crystals in a small quantity to prevent the TN liquid crystals from suffering so-called reverse domain, and it can also be used as an STN liquid crystal, etc.
• Sc compounds to which the optically active compound of general formula (I) according to the present invention can be added as a chiral dopant to prepare Sc liquid-crystal compositions include phenyl benzoate-type compounds represented by the following general formula (A) and pyrimidine-type compounds represented by the following general formula (B): wherein R a and R b are identical or different and independently represent a straight-chain or branched alkyl, alkoxyl, alkoxycarbonyl, alkanoyloxy, or alkoxycarbonyloxy group; wherein R a and R b are the same as those in general formula (A) above.
• compounds represented by the following general formula (C), which includes general formulae (A) and (B), may be used for the same purpose: wherein R a and R b are the same as those in general formula (A); are identical or different and independently represent or halogen-substituted groups derived therefrom; and Z a represents -COO-, -OCO-, -CH2O-, -OCH2-, -CH2CH2-, -C ⁇ C-, or a single bond.
• three-ring compounds represented by general formula (D) may be used: wherein R a and R b are the same as those in general formula (A); are identical or different and are the same as in general formula (C) above; and Z a and z b are identical or different and are the same as Z a in general formula (C) above.
• the liquid-crystal composition obtained by incorporating the optically active compound of general formula (I) according to the present invention into an Sc compound or Sc liquid-crystal composition, may be sandwiched between two transparent glass electrodes in such a manner that the composition is enclosed in the form of a thin film about 1 to 20 ⁇ m thick.
• This construction can be used as a display cell, but in order to obtain good contrast, the cell should be of a monodomain structure in which orientation is uniform. Many attempts have so far been made to obtain such monodomain cells.
• the liquid-crystal material is required to show a phase sequence of (I) - (N * ) - (S A ) - (Sc * ), and to have elongated helical pitches in the N * phase and Sc* phase.
• an increased helical pitch can be obtained by blending suitable amounts of chiral compounds having opposite twist directions, this preparation of a chiral dopant can be made easy with the optically active compound of general formula (I) according to the present invention because the compound of general formula (I) induces a sufficiently large helical pitch especially in an N * -phase temperature range, as described above.
• optically active compound represented by general formula (I) In the optically active compound represented by general formula (I) according to the present invention, at least two asymmetric carbons (C* and C ** ) are present.
• the absolute configuration of C ** depends on that of the optically active epoxide which is represented by general formula (III) and was used as a raw material to synthesize the compound of general formula (I). If the absolute configuration in the epoxide was (R), that of C ** is (S). If the absolute configuration of the epoxide was (S), that of C ** is (R).
• the polarity of the spontaneous polarization induced by the optically active compound of general formula (I) according to the present invention depends on the absolute configuration of the asymmetric carbon C * , in the case where the composition does not contain asymmetric carbons other than those of the compound of general formula (I). That is, C * of the (R) configuration results in the polarity of ⁇ , while (S) configuration results in ⁇ .
• the above is a great advantage in preparing a chiral dopant.
• the compound of general formula (I) is combined with any other optically active compound, the helical pitch can be elongated without causing the induced spontaneous polarizations to weaken each other. Further, even by use of the compound of general formula (I) alone, helical pitch can be easily adjusted without impairing induced spontaneous polarization.
• the structures of compounds were determined by nuclear magnetic resonance spectroscopy (NMR), infrared spectrophotometry (IR), and mass spectrometry (MS). Phase transition temperatures were measured by means of both a polarizing microscope equipped with a temperature-regulating stage and a differential scanning calorimeter (DSC).
• NMR nuclear magnetic resonance spectroscopy
• IR infrared spectrophotometry
• MS mass spectrometry
• Phase transition temperatures were measured by means of both a polarizing microscope equipped with a temperature-regulating stage and a differential scanning calorimeter (DSC).
• IR data (KBr) indicates measurement on formed tablets
• (neat) indicates measurement on liquid films
• (Nujol) indicates measurement on suspensions in liquid paraffin.
• NMR data (CDCl3) and (CCl4) indicate solvents, while “s” means a singlet, "d” a doublet, "t” a triplet, "q” a quartet, and "m” a multiplet.
• the product obtained above was further purified by recrystallization it from ethanol, and the phase transition temperatures of the purified compound were measured. As a result, this compound showed an S A phase at temperatures below 136°C, and showed, at temperatures below 113.5°C, a chiral smectic phase which was not identified with respect to smectic structure.
• the melting point of the compound was 70°C.
• Example 14 The same procedures as in Example 14 were repeated except that 4-octyloxybenzoyl chloride was used in place of 4-(4-octyloxyphenyl)benzoyl chloride, thereby obtaining the desired compound as colorless crystals.
• phase transition temperatures of this compound are shown in Table 2.
• Example 14 The same procedures as in Example 14 were repeated except that 4-[4-((R)-1-methylheptyloxy)-phenyl]benzoyl chloride was used in place of 4-(4-octyloxyphenyl)benzoyl chloride, thereby obtaining the desired compound as colorless crystals.
• Example 14 The same procedures as in Example 14 were repeated except that 4-(5-hexylpyrimidin-2-yl)benzoyl chloride was used in place of 4-(4-octyloxyphenyl)-benzoyl chloride, thereby obtaining the desired compound as colorless crystals. Identification data are given below.
• Example 14 The same procedures as in Example 14 were repeated except that (1S,2S)-1-cyano-2-hexyl-1-(4-hydroxyphenyl)cyclopropane as obtained in Example 12 was used as the raw compound, thereby obtaining the desired compound as colorless crystals.
• Example 18 The same procedures as in Example 18 were repeated except that 4-octylbenzoyl chloride was used in place of 4-(4-octyloxyphenyl)benzoyl chloride, thereby obtaining the desired compound as colorless crystals.
• phase transition temperatures of this compound were measured. As a result, it showed an S A phase at temperatures not higher than 46.5°C, and its melting point was 48.5°C.
• the product obtained above was further purified by recrystallization from ethanol, and the phase transition temperatures of this purified compound were measured. As a result, the compound showed an S A phase below 103.5°C, and its melting point was 92.5°C.
• Example 23 The same procedures as in Example 23 were repeated except that (S)-4-(2-propoxypropanoyloxy)-benzoyl chloride was used in place of trans-4-heptylcyclohexanecarbonyl chloride, thereby obtaining the desired compound.
• This compound did not crystallize even when left at a low temperature for a prolonged period of time and, hence, its melting point could not be measured.
• the compound however, showed an S A phase at temperatures not higher than 39°C.
• Base liquid crystal (A) consisting of the following ingredients was prepared.
• This composition showed the following phase transition temperatures (°C).
• Base liquid crystal (B) consisting of the following ingredients was also prepared.
• This composition showed the following phase transition temperatures (°C).
• base liquid crystal (C) consisting of the following ingredients was prepared.
• This composition showed the following phase transition temperatures (°C).
• base liquid crystal (D) consisting of the following ingredients was prepared.
• This composition showed the following phase transition temperatures (°C), but its melting point could not be measured.
• Example 14 to 24 Compounds Nos. 1 to 11 in Table 2 were added to the above-obtained base liquid crystals in amounts of 5 to 15%, thereby preparing Sc * liquid-crystal compositions.
• the phase transition temperatures of each of the thus-obtained compositions are shown in Table 3.
• Example 25 Each Sc* composition obtained in Example 25 was heated to an isotropic liquid (I) phase. This composition was packed in a glass cell comprising two transparent electrode plates (aligned by polyimide-coating-and-rubbing treatment) about 2 ⁇ m apart, thereby preparing a thin film cell.
• I isotropic liquid
• each of the thus-prepared cells was gradually cooled to room temperature to obtain a cell in which the composition was in a uniformly oriented Sc * phase.
• the composition employing the compound of Example 21 and that employing the compound of Example 24 showed very large helical pitches in N * phase, and by gradually cooling the two cells to room temperature, monodomain cells were obtained in which the compositions were in uniformly oriented Sc* phase.
• optically active compound of general formula (I) shows a liquid-crystal phase and, when incorporated as chiral dopant into other Sc * liquid-crystal composition or Sc liquid-crystal composition, can induce a large spontaneous polarization to achieve high-speed response.
• optically active compound represented by general formula (I) and the intermediate therefor, both according to the present invention can be easily produced industrially, and these compounds are colorless and chemically stable to light, water, heat, etc. Therefore, they are of good practical use.
• the liquid-crystal material of this invention which comprises a chiral smectic liquid-crystal compound or composition can attain a high-speed response time as short as about 30 ⁇ sec and, hence, is extremely useful as a light-switching element for display.

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  • 1990-12-20 US US07/630,591 patent/US5064564A/en not_active Expired - Lifetime
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